Computer systems generally utilize auxiliary memory storage devices having media on which data can be written and from which data can be read for later use. A direct access storage device (disk drive) incorporating rotating magnetic disks is commonly used for storing data in magnetic form on the disk surfaces. Data is recorded on concentric, radially spaced tracks on the disk surfaces using recording heads. Read heads are then used to read data from the tracks on the disk surfaces. Read and write heads can be formed together on a single slider.
FIG. 1 illustrates the air bearing surface (ABS) view of a typical inductive write head 100. In a typical head, an inductive write head includes a coil layer (not shown) embedded in an insulation stack (not shown) that may have first, second and third insulation layers, the insulation stack being located between first and second pole piece layers 102, 104. A gap is formed between the first and second pole piece layers 102, 104 by a gap layer 106 at an air bearing surface of the write head. The pole piece layers are connected at a back gap. Currents are conducted through the coil layer, which produce magnetic fields in the pole pieces 102, 104. The magnetic fields fringe across the gap at the ABS for the purpose of writing bits of magnetic field information in tracks on moving media, such as in circular tracks on a rotating magnetic disk or longitudinal tracks on a moving magnetic tape.
As head sizes become smaller, the flux 108 produced by the pole piece layers 102, 104 can create a fringing field that causes adjacent track interference that can overwrite and/or realign data bits in adjacent tracks. Fringing fields are reduced somewhat by forming a notch 110 in the first pole piece layer 102. However, if the notch 110 is made too large, the flux necessary to write to the data is choked.
It has been found that producing an angled “shoulder” 202 in the first pole piece layer 102 below a straight portion 204 of the first pole piece layer 102, such as in the head 200 shown in FIG. 2, form a steep shoulder notch that minimizes fringing fields while increase the on track writing field. This enables better on track writability while reduces the adjacent track interference. Note the difference in flux patterns 108 in FIGS. 1 and 2. It has also been found that this design also increases overwrite, i.e., the field that overwrites data on the media. Further, flux leakage is reduced, concentrating the field at the ABS.
Prior art methods proposed for creating a steep shoulder notch such as that shown in FIG. 2 require either an additional photo layer or cause degrading of the pole width and reduced pole shape control capabilities. The additional photo layer adds to the cost of manufacture. Degradation of the pole width and/or pole shape reduces performance of the head. Thus, both of these options are undesirable.
What is therefore needed is a way to form the desired tapered shoulder without use of an additional photo layer. What is also needed is a way to form the desired tapered shoulder that does not affect the track width and pole shape control.